Process of sulphation



35 by weight.

Patented May 7, 1940 NI ED STATES PATENT OFFICE rnocsss or SULPHATION Max Engelmann, Wilmington, Del., assignor to E. I. dnPont de Nemours & Company, 711- mingt'on, DeL, a corporation of Delaware --No Drawing. Application August 27, 1938;

V Serial No. 227,062

7 Claims. (or. 260-460) 10 method of sulphating aliphatic compounds which contain 8 or more carbon atoms and a hydroxyl group attached to a secondary or tertiary carbon atom. A further object is to sulphate said aliphatic compounds inthe presence of a cheap 15 diluent which does not need to be recovered and which imparts a pleasant odor to the sulphation product. A still further object is to employ a diluent in the sulphation procedure which tends .to prevent side reactions and permits one to ob- 20 tain high yields of sulphation products which have an improved solubility and a better physical appearance. after. i

These objects are accomplished by the follow ing invention which relates to the sulphation of aliphatic compounds which contain 8 or more carbon atoms and a hydroxyl group attached to a secondary or tertiary carbon atom in the presence of an alkyl ester of an aliphatic monocar.-

30 boxylic acid containing from '1 to 8 carbon atoms wherein the alkyl group in said ester contains from 1 to 8 carbon atoms. I

The invention is illustrated, but not limited, by the following examples in which the parts are Example! 50 parts of pentadecanol-8 were dissolved in 46.4 parts of ethyl acetate. 30.6 parts of chlorosulphonic acid were slowly added at a temperature of to C. over a period of 1 hours. At the end of this time a testdrop gave a clear solution in water. The sulphation mass was poured into an aqueous sodium hydroxide solution. Two layers formed. The upper oily layer contained the sodium pentadecyl-B sulphate. On evaporating with gentleheating on the steam bath a light colored waxy solid showing excellent water solubility and high wetting-out action was 50 obtained.

Example 2 Example 3 169 parts of chlorosulphonic acid were dissolved w in 161 partsof propyl acetate. 300 parts of Other objects will appear herein-v molten pentadecanol-8 were added over a period of two hours at -10 to 5 C. The product was worked up as in Example 1.

Example 4 200 parts of 1,12-octadecanediol were dissolved in 330. parts of ethyl acetate. 197 parts of chlorosulphonic acid were added over a period of two hours. The product was worked up as in Examplel. The octadecanediol was converted to the extent of about 85% into the corresponding disulphate.

Example 5 30 parts of alpha hydroxy stearic acid were mixed with 50 parts of methyl acetate. parts of chlorosulphonic acid were slowly added while stirring at a temperature of 25 to 30 C. During the sulphating process the acid went into solution. After further agitation for hour a test drop gave a clear solution in water. The sulphation mass was poured into 200 parts of a 10% aqueous solution of sodium hydroxide. After the addition ofabout parts of sodium chloride two layers were formed. The upper layer contained the di-sodium salt of the sulphate ester of hydroxy stearic-acid. To isolate the sodium salt in dry form the lower layer was. decanted off and the remaining very viscous mass dried on a steambath. The residue was a waxy solid showing excellent water solubility. The water solution showed all the characteristics of a solution heptyl, and octyl esters of formic, acetic, propionic, butyric, valeric, caproic, heptoic, and caprylic acids is contemplated. High molecular weight esters may be employed such as octyl acetate,

butyl propionate and ethyl caprylate. However,

lower molecular weight esters such as methyl formate, ethyl formate, propyl 'formate, methyl acetate, ethyl acetate, and propyl acetate are cheaper, and hence from an economic viewpoint, they are more feasible to use. Propyl acetate is the preferred diluent for use in the sulphation of pentadecanol-8.

chlorosulphonic acid is the preferred sulphating agent but other strong sulphating agents such as oleum, sulphuric monohydrate, bromosulphonic acid and sodium chlorosulphonate may be employed.

The temperature at which the reaction is run may be varied over wide limits, the optimum temperature being dependent upon the nature of the hydroxy compound being sulphated. Thus, while temperatures orirom --30 to 35 C. are preferred, lower and higher temperatures may be employed in this reaction.

The method of carrying out the reaction with respect to the order of addition of the reagents also lends itself to several variations. The chlorosulphonic acid can be dissolved in the ester and added to the hydroxy compound; the hydroxy compound can be added to a solution of chlorosulphonic acid in the ester, or the chlorosulphonic acid can be added to a solution of the hydroxy compound in the ester.

The procedure described in this specification is useful for sulphating any aliphatic compound which contains 8 or more carbon atoms and a hydroxyl group attached to a secondary or tertiary carbon atom. This invention is most useful in the preparation of secondary alkyl sulphates containing 8 or more carbon atoms by sulphation of secondary aliphatic alcohols containing 8- or more carbon atoms. Secondary alcohols which may be suphated in accordance with the present invention include tridecanol-7, 3,9-diethyl tridecanal-6, 5,11-diethyl pentadecanol-S, octanol-2, pentadecanol-i, and pentadecanol-S. Tertiary alcohols which can be sulphated according to the processes disclosed herein include diheptyl ethyl carbinol and dioctyl methyl carbinol. Other aliphatic compounds which contain a hydroxyl group attached to a secondary or tertiary carbon atom which can be sulphated by the methods disclosed-herein include ethers such as 12-hydroxy octadecyl methyl ether and alpha, alpha bis(2-etliylhexy) glycerine ether; hydroxy ketones such as capryloin; hydroxy acids and their esters such as alpha hydroxy stearic acid, the

methyl ester of alpha hydroxy stearic acid, ricinoleic acid, methyl ricinoleate, the laur'yi ester of alpha hydroxy propionic acid, bis(2-ethylhexyl) malate, triethyl citrate, and dihexyl tartrate.

It has been found that the presence of these rs exerts a profound influence upon the reaction oi chlorosulphonic acid upon hydroxy com- DDllilidS. It is not clear just what is the mechanlsirl of the reaction, but it is apparent that the ester does not function as an inert diluent. Thus in the case of secondary alcohols, treatment with the usual sulphating agents, such as chlorosulphonic acid, leads to dehydration of the alcohol and the formation of valueless water-insoluble, dark colored products. If secondary alcohols are treated with chlorosulphonic acid in the presence of typical diluents such as carbon tetrachloride, ethylene dichloride, or chloroform, side reactions leading to water-insoluble, dark colored products are obtained. When, however, secondary alcohols are reacted according to the present invention, smooth and eficient conversion of the alcohols into aiiryl sulphates takes place.

This application covers a particularly eflicient and smooth method for sulphating aliphatic compounds which contain 8 or more carbon atoms and a hydroxyl' group attached to a secondary or tertiary carbon atom. The mildness of the reac- JiOll makes it applicable to very labile compounds which ordinarily undergo undesirable side reactions when treated with sulphating agents. In spite of the mildness oi the reaction, high yields and accordingly very pure products can be obtained.

Secondary and tertiary aliphatic alcohols cannot be satisfactorily sulphated by the ordinary means such as chloro-sulphonic acid or sulphuric acid alone or in the presence of inert diluents. However, when these alcohols are treated in the presence of aliphatic esters with chlorosulphonic acid, smooth and efilcient sulphation is obtained. Since these esters are cheap diluents, it is not necessary to recover them. They may be permitted to remain in the sulphation product to which they will impart a pleasant odor.

The above description and examples are intended to be illustrative only and not to limit the scope of the invention. Any departure therefrom which conforms to the spirit of the invention is intended to be included within the scope of the appended claims.

I claim:

1. A method 01 sulphating a saturated aliphatic compound which contains at least 8 carbon atoms and a hydroxyl group attached to a secondary carbon atom which comprises reacting said aliphatic compound with a strong sulphating agent in the presence of an alkyl ester of an aliphatic monocarboxylic acid containing from 1 to 8 carbon atoms wherein the alkyl group in said ester contains from 1 to 8 carbon atoms.

2. A method of preparing a secondary alkyl sulphate containing at least 8 carbon atoms which comprises reacting a secondary aliphatic alcohol containing at least 8 carbon atoms with chlorosulphonic acid in the presence of an ester selected from the group consisting of the methyl, ethyl, and propyl esters of formic and acetic acids.

3. A method of preparing pentadecyl-B sulphate which comprises reacting pentadecanol-8 with chlorosulphonic acid in the presence of propyl acetate.

4. A method of preparing pentadecyl-8 sulphate which comprises reacting pentadecanol-B with chlorosulphonic acid in the presence of an ester selected from the group consisting of the methyl, ethyl, and propyl esters of formic and acetic acids.

5. A method of preparing pentadecyl-8 sulphate which comprises reacting pentadecanol-8 with chlorosulphonic acid in the presence of ethyl acetate.

6. A method of preparing an alkyl sulphate containing at least eight carbon atoms which comprises reacting an alcohol selected from the group consisting of secondary and tertiary aliphatic alcohols containing at least eight carbon atoms with a strong sulphating agent' in the presence of an alkyl ester of an aliphatic monocarboxylic acid containing from one to eight carbon atoms where in the alkyl group in said ester contains from one to eight carbon atoms. 1

'7. A method of preparing an alkyl sulphate containing at least eight carbon atoms which comprises reacting an alcohol selected from the group consisting of secondary and tertiary aliphatic alcohols containing at least eight carbon atoms with chlorosulphonic acid in the presence of an ester selected from the group consisting of the methyl, ethyl, and propyl esters of formic and acetic acids.

MAX ENGELMANN. 

